It is well known organic sulfur widely exists in a feed gas produced by a chemical method using coal, gas and oil as raw materials, and its presence will cause poisoning deactivation of a catalyst in the subsequent processes. More and more studies and researches have been carried out for developing new technologies, such as preparation technologies of a feed gas using a low-grade coal and a coke-oven gas, coal-gas poly-generation technologies, and low-temperature steam transformation technologies.
Carbonyl sulfide is neutral or slightly acidic, and has a stable chemical property, so it is difficult to be removed completely by using a conventional desulphurization method. There are two removal methods of carbonyl sulfide in industry, i.e. dry desulfurization and wet desulphurization. Fine desulfurization is difficult to be realized by the wet desulphurization as restricted by factors such as chemical equilibrium, so carbonyl sulfide is generally removed by the dry desulfurization method wherein the carbonyl sulfide is converted into hydrogen sulfide by hydrogenolysis or hydrolysis in order for removal. Dry desulfurization generally comprises two methods, i.e. hydrolysis method and hydrogenolysis method. There are two kinds of catalysts for carbonyl sulfide hydrolysis at home and abroad. The first one is a simple conversion type hydrolysis catalyst which only has conversion effect on the carbonyl sulfide and has to be used in combination with a desulfurizer such as zinc oxide and activated carbon. The second one is conversion-adsorption type hydrolysis catalyst which not only has a conversion effect on an organic sulfur such as carbonyl sulfide, but also has an absorption effect on hydrogen sulfide converted from the organic sulfur, so it can be used alone for removal of trace sulfur. In recent years, a conversion-adsorption type bifunctional desulfurizer has drawn a great attention. For example, Chinese patent application CN1069673A discloses a catalyst for organic sulfur hydrolysis at room temperature, comprising potassium carbonate in an amount of 2-25 wt % and a spherical γ-Al2O3. When this desulfurizer is used at room temperature, the conversion rate of carbonyl sulfide reaches up to 95%, and it is capable of converting the carbonyl sulfide while absorbing hydrogen sulfide. Although the above desulfurizer for carbonyl sulfide conversion can reach a higher conversion rate at room temperature, the disadvantage is that it is just applicable to treat carbonyl sulfide with a lower concentration, such as no more than 30 mgS/m3, but is not applicable to treat carbonyl sulfide with a high concentration. Therefore, the problem to be solved in the prior art is how to develop a desulfurizer that can realize efficient conversion and absorption of a high-concentration carbonyl sulfide. In a chemical feed gas, CS2 generally exists in an amount of approximately 10% of the amount of COS. CS2 is a polar molecule and its hydrolytic process is as below:CS2+H2O→COS+H2S  (1)COS+H2O→CO2+H2S  (2)CS2+CO2→2COS  (3)
In the above process, CS2 is converted into COS. The hydrolysis conversion rate of CS2 is subjected to influences of carbonic oxide and hydrogen sulfide atmospheres, and it is difficult to realize a complete removal of CS2. In the prior art, Chinese patent application CN10112123A discloses a catalyst for carbon disulfide hydrolysis under moderate temperature, comprising a spherical γ-Al2O3 as a carrier, alkali metal oxide K2O as a promoter, and zirconium dioxide ZrO2 and a rare-earth metal oxide La2O3 as a modifier, and prepared by an incipient-wetness impregnation method comprising impregnating the promoter and modifier followed by calcinations. The obtained catalyst has a better performance against carbon deposition and side reactions not contributing to the conversion.
Although the above catalyst has a high efficiency for treatment of CS2 under certain conditions, it is only applicable to treat CS2 with a concentration range of 200-500 mgS/m3, but not applicable to treat CS2 with a high concentration. Therefore, the problem to be solved in the prior art is how to develop a desulfurizer which can achieve efficient conversion and absorption of a high-concentration CS2.